True, though in my lifetime I've done about 250-300 flights and that has happened very rarely. One way to avoid it is to cough up for the exit row (which I do anyway for the legroom) - neither of those would be allowed to sit there. But even away from that, stress is in some ways reduced by not being able to move seats - whether you should or not, and the logistics of doing it if you have lots of bags, are *themselves* stressors.
I've had my seat kicked by a toddler from several times, and you don't need to be sitting next to a grumpy baby for the noise to be a distraction. I don't need the extra legroom, and with an exit row seat, your bag has to go in the overhead bins and the middle seat will always be taken. Its a moot point now, as all of the flights I've been on in the last few years have had allocated seating.
There is another way to avoid the stress of lots of bags ...
I go with one of my late colleagues' views (he was a classic and slightly eccentric true English gentleman - always wore a bow tie and a well-fitting suit) - "always travel heavy, you never know what you might want". With a modern trolley case, even a very large and heavy one, this really is not made difficult at all.
It seems that am pretty good at knowing what I want, and I've got a credit card for the stuff I don't have with me.
If you have a bag that goes in the hold, it needs to be sturdy or, given enough flights, it will get damaged. That makes it heavy, and if its rigid, then its inflexible, and you can't fit it into small gaps on luggage rack, or in the boot of a car. I hate the noise of trolley bags being dragged along a pavement, and if you use the wheels outside, the bag ends up grubby. Stairs are a pain with heavy luggage.
And in the 250-300 flights noted above, I've had luggage delayed twice.
I have colleagues who check bags in, and I hear of their hassles. I haven't had any luggage delays in my last 300 flights, but I've only checked stuff in a couple of times out of those.